[Birdtalk] California Gull vs Ring Billed Gull

[Lofthouse]

I sometimes buy a bag of popcorn at Walmart in Logan then go out in the parking lot and feed the birds.  You can easily see the marks that differentiate these two species when they are eating out of your hand, however when you have 2000 or so birds sitting out on the Hyrum dam at 1/4 to 1/2 mile away, Forget it!   I don't care how much you paid for your scope.   IMO

Here are some photos for you to look at.  You can compare many of the field marks from these photos.  I cannot for the life of me see any difference in the shape of the bill.  The California does have a spot of red on the lower mandible.  The Color of the legs is often yellow in the ring-billed and rather greenish in the california.  The ring-billed is a bit smaller.
The ring-billed has a lighter colored mantle.  The iris is yellow in the ring-billed.  Some have mentioned a slimmer look in flight, that is a tough call, and that is not evident in any of these photos.  Maybe that can be my next photo challenge? 

I cannot see any appreciable difference in the white spotting on the wing tips.  

The field guides show some  brownish streaking on the head and neck of the California, but most of these have a very white head and nape.  

What do you think?

http://donce.lofthouse.com/jamaica/gull.htm

Jim
  ----- Original Message ----- 
  From: birdnet at skylace.net 
  To: birdtalk at utahbirds.org 
  Sent: Saturday, April 05, 2008 11:21 AM
  Subject: [Birdtalk] California Gull vs Ring Billed Gull



  Is there any reliable way to distinguish
  California Gulls from Ring Billed Gulls
  at a distance?

  The reason I ask, is that during the winter
  I sat on the flyway where gulls were coming
  in to spend the night on a lake. About 200
  gulls came close enough for me to see the
  eyes. Every gull who's eyes I could see 
  had yellow eyes (ring-billed).  

  The next day one of my favorite posters to
  this group said that s/he had observed a flock
  of California gulls at the lake.

  So I went back to the lake and observed another
  hundred gulls at close distance, and every
  one of them had yellow eyes (ring-billed).

  I think the other poster was wrong about the
  identification even though s/he is very 
  knowledgeable about the birds of Utah.

  Beyond about 100 feet I am clueless about whether
  a gull is a California Gull or a Ring-Billed Gull,
  and if even an expert goofs I wonder if eBird might
  benefit from a California/Ring-Billed category?


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